On a quiet morning last week outside Stevensville, a pair of juvenile moose joined a herd of deer foraging in a farmer’s field near the Bitterroot River.
“They're definitely thick in the river bottom,” said FWP Bitterroot biologist Rebecca Mowry. “Almost every time I hike in the Hamilton parks, I run into a moose or moose sign.”
While sightings of America’s largest deer species aren’t as common as interactions with smaller ungulates, moose can regularly be found in the Bitterroot Valley this time of year.
The origin of the word moose comes from the Algonquin word “moosu,” which means “bark stripper,” and the willow and cottonwood trees that line the Bitterroot River can make for inviting habitat. They also are attracted to recently burned areas and other riparian zones like creeks.
“The Bitterroot River bottom in particular, it's pretty good moose habitat,” Mowry said. “They really like deciduous shrubs and trees to eat like willows and cottonwoods. They typically will make pretty good use of those deciduous plants.”
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Standing 6 feet tall at the shoulder and weighing in at more than 1,000 pounds, moose can be an intimidating force in the wild. Mowry said that people who live here should expect to potentially run into moose when they are out hiking in the Bitterroots or in the riverbottom areas. According to Mowry, it’s best to back away slowly and try to get out of the area without making the moose angry. People should know that cows with calves are going to be more aggressive, as will bulls during the rut, which is usually about September to early October.
“So just like with any wildlife here in the Bitterroot, people should just know that we have them and know that they're dangerous and be aware and try not to have encounters,” Mowry said.
While moose numbers can be hard to pin down since they’re solitary animals and don’t group up like other ungulates, Bitterroot Valley “moose are generally doing okay,” Mowry said.
“We do surveys for mule deer and for elk from a helicopter and from a plane, we also survey bighorn sheep and mountain goats from the air as well, but you just can't do that with moose,” Mowry said. “They live in really dense vegetation most of the time. They're solitary, they don't live in these big herds like elk and sometimes deer do. So you just cannot effectively survey them in the Bitterroot from an airplane.”
Typically FWP biologists rely on hunters to tell them how many moose they’ve seen or harvested as a gauge of populations, but researchers are finishing up a 10-year study that they hope will shed more light on just how many moose are roaming the mountains of Montana.
The study, headed by FWP research biologist Nick DeCesare, focused on three main areas: the Rocky Mountain Front, the Cabinet Mountains and the Big Hole.
“What we're working on now is kind of similar to the way that we count wolves,” DeCesare said. “We've been collecting hunter sightings data in kind of a standardized format during the hunting season with the phone surveys that we use, and adding moose sightings as part of that protocol. And that's something that we're hoping will help with estimating numbers and trends, more at a statewide scale. It's actually in review right now.”
While it's difficult to estimate absolute numbers, biologists do have indices that help them look for trends in population, such as hunter success rates, and number of hunter days per successful harvest.
“Those things were all pointing towards kind of a decline since the mid '90s," DeCesare said. "And that's where some of the motivation came to start this 10-year research study. The research study has been really drilling into the details of those numbers in terms of estimating survival rates, and recruitment rates, all the kinds of things — the nuts and bolts behind whether a population is going up or down.”
According to DeCesare, the good news is that all three of those populations seem to be at least stable, with one of them, the Rocky Mountain Front, increasing despite heavy infestations of winter ticks. The ticks can cause blood loss and moose infected with them tend to rub most of their hair off trying to remove the insects.
“So it doesn't mean that things haven't changed, longer term since the '90s,” DeCesare said. "But at least in the last 10 years, in these three focal areas that the populations look stable."
The study has also found that moose in the Big Hole suffer from arterial worm infestations. The worm clogs up their carotid artery and can cause moose to get frostbite on their heads and also go blind.
But in the Bitterroot, the biggest pressure on moose populations is human development, according to Mowry.
“As these ag fields and timber land get turned into subdivisions, it just really decreases the amount of space that is available for these animals,” Mowry said. “Moose still seem to be doing okay despite that, but of course, that is causing humans to come into contact with moose a lot more than they used to. We’ve had issues, self-defense issues were some moose have been shot, and then the moose coming into Hamilton and being fed by people and having to be relocated. All those things are going to happen more when you have development into moose habitat.”
